Vehicle on-board electronic systems in heavy-duty trucks have been defined by the American Trucking Association (ATA). Certain recommended practices of the Society of Automotive Engineers (SAE) relating to on-board electronic vehicle systems, in particular J1708, J1587, and J1809, conform to these ATA requirements. Further, compliance with SAE J1809 is preferred in heavy-duty vehicles. J1809 is a recent SAE RP that specifies waveform characteristics for vehicle speed and engine speed signals. J1809 requires electronic modules to sink and source high levels of current, more than those provided by today's typical modules.
For compliance with such ATA requirements, a manufacturer of heavy-duty trucks must provide a conforming on-board electronic vehicle system. Since electronic engine management is an essential consideration in an on-board electronic vehicle system, it too must conform to ATA requirements. Yet, time and costs associated with truck design and manufacture for the size and demands of the heavy-duty truck market are such that it may be prohibitive to design, fabricate, and inventory total on-board electronic vehicle systems which include integral electronic engine management systems that have compatibility with ATA requirements and the corresponding SAE recommended practices. This is because highway trucks are ordered by customers on a highly customized basis, and the volume of highway truck production is comparatively small when measured against the total automotive vehicle market.
The present invention arises in part through the recognition that an electronic engine management system need only to appear to the vehicle network that it conforms with ATA requirements and corresponding SAE recommended practices. In one respect, the present invention relates to a total on-board electronic vehicle system which is fully compatible with ATA requirements and the corresponding SAE recommended practices for heavy trucks, yet uses an EEC module that is already commercially available even though that EEC module is itself not directly compatible with such ATA requirements and the corresponding SAE recommended practices. By utilizing an available EEC module, especially one that has already been tooled and is being fabricated on a commercial production basis, considerable savings in design and development time and in design, development, and fabrication costs may be reaped. This is especially important to the highway truck manufacturer because of the nature of the market, as described above.
Briefly, the present invention is able to take advantage of a known EEC module which is not directly compatible with ATA requirements and the corresponding SAE recommended practices by providing a special new and unique electronic module that in effect provides a bi-directional electronic interface between a vehicle network's ATA-compliant data link and such an EEC module. This special electronic module is however much more than merely a "translator" of electronic data passing between the network and the EEC module. It is operatively associated with certain other components of the vehicle in a manner that provides a new and unique organization for operatively relating these other components with the vehicle network and the EEC module.
Internal combustion engines for heavy-duty trucks have different displacements and ratings. Each combination of engine displacement and rating requires an engine management computer that is uniquely tailored to the engine's specific combination of requirements. Even though an engine management computer may possess hardware capabilities that enable it to be potentially used with a number of specific engines, it must nevertheless be software-adapted for a specific engine. Given the significant number of different displacement/rating combinations, a large number of unique engine management computers is necessary because of the need to program each for the specific displacement/rating of a given engine. As one can appreciate, this would introduce a need for many unique part numbers into a business system, adding cost and complexity to service and inventory requirements. Accordingly, it is a desirable objective to minimize the number of unique parts that are required to serve a large number of engine displacement/rating combinations, and as will be seen herein, that objective is fully accomplished by the present invention.
A further complicating factor in the case of heavy-duty or highway trucks is that a variety of optional features must be offered, and some of these involve engine management. For example, road speed limiting and cruise control are two such features. An engine management computer must take the presence or absence of such features into account, and if it cannot, the possibility of offering other than a standard set of features, which could be neither individually deleted nor individually added to, would be foreclosed, thereby seriously limiting the ability of the vehicle manufacturer to accommodate purchasers' requests for specific combinations of option features.
The present invention provides a capability for programming the special electronic module with data for a particular engine displacement/rating combination selected from a number of different such combinations and with data for a particular combination of option features selected from a number of different option features.
The special electronic module contains hardware that can be programmed with data that allows it to be used with a vehicle containing a particular engine and a particular combination of option features. It is the particular data that is programmed into the module that adapts what is otherwise a basic standard module into a custom one for the particular vehicle. Certain data is programmed into the module at the factory based on equipment installed. Other data may be programmed by the dealer or by the owner, assuming that they possess suitable equipment. To the extent that the known EEC module does not possess architecture for accommodating all the needs of the system, such architecture is provided in the special electronic module.
In accordance with another aspect of the invention, the special electronic module is endowed with different levels of programming security. Some data should be alterable, if at all, only by the vehicle manufacturer, and that data would have the highest level of security. Other data may be programmable, or alterable, by the dealer or owner, in which case it is assigned a lower level of security. Compatibility checks are also provided to assure that the programmed module is fully compatible with the hardware and software with which it is connected in the vehicle in which it is installed. This will help to safeguard against the possibility of hardware or software incompatibility, especially at times of service after a vehicle is in use.
A still further aspect of the invention involves the ability to detect the presence or absence of the vehicle speed sensor. This is important, especially at vehicle launch, and if the speed sensor is found to be absent, the vehicle system is enabled to take certain actions.